The Spymaster

This one tells the tale of Guy Cheshire, a British admiral heading a bureau of naval intelligence, engaged in a struggle against a network of Italian spies, headed by a metal broker named Florestan, and which had enmeshed two naval aides and two Italian countesses. The tale is set against the backdrop of the preparations for war on the part of (the usually unnamed) Germany and Italy. Oppenheim refers to them euphemistally for most of the book but capitulates towards the end and is explicit.